This invention pertains to the field of rope (cable) hitches and terminations, and in particular, to a pivoting termination for an elevator rope.
An elevator is a hoisting and lowering mechanism equipped with a car or platform which moves in guides in a vertical direction. Electric elevators are suspended and moved by a series of pulleys (sheaves) and cables (ropes). In a typical arrangement, a wire rope is reeved over a number of sheaves, terminating in a hitch on the top and bottom of the car. Care is typically taken during the installation to mount the various sheaves in the machine room or on the car in such a manner as to ensure only vertical strain is applied to the wire ropes terminating in hitches. This reduces metal fatigue on the wire rope that would occur if subjected to horizontal bending forces.
Coated steel belts (CSB""s) have been developed which are strong enough to replace the traditional wire cables used with elevators. These CSB""s permit sheave and hitch arrangements that were not practical when using wire ropes. In an arrangement where the CSB hitch or termination is subjected to horizontal forces as well as vertical forces, metal fatigue is a concern.
Briefly stated, a pivoting hitch for an elevator rope includes a horizontal shaft or ball having a circular base and a flat top. The shaft or ball rests on a seat. An elevator rope is connected to a rod which passes through a hole in the shaft or ball and is suspended on the flat part of the shaft or ball by a spring. The shaft is used when multiple ropes are used to suspend an elevator car. When used with an overslung or underslung elevator car suspension, the pivoting hitch keeps the rope angles on both sides of the elevator car the same.
According to an embodiment of the invention, a pivoting hitch for an elevator rope includes a shaft being shaped as a right cylindrical prism, with a base having a circular arc joined at both ends by a straight line whereby the shaft has a flat portion and a rounded circular portion; at least one hole through the shaft, the at least one hole being substantially perpendicular to the flat portion; the rounded circular portion of the shaft resting on a seat, wherein a shape of the seat that makes contact with the shaft is congruent to the rounded circular portion of the shaft; the seat resting on a lower hitch plate; the lower hitch plate having at least one hole therein; at least one rod passing through the at least one hole in the lower hitch plate, through the at least one hole of the shaft, and through at least one spring; and an end of the at least one rod being connected to a termination for a rope, and another end of the at least one rod being connected to the spring.
According to an embodiment of the invention, a pivoting hitch for an elevator rope includes a shaft being shaped as a right cylindrical prism, with a base having a circular arc joined at both ends by a straight line whereby the shaft has a flat portion and a rounded circular portion; at least two holes through the shaft, the at least two holes being substantially perpendicular to the flat portion; the rounded circular portion of the shaft resting on a seat, wherein a shape of the seat that makes contact with the shaft is congruent to the rounded circular portion of the shaft; the seat resting on a lower hitch plate; the lower hitch plate having at least two holes therein; at least two rods each passing through a separate one of the at least two holes in the lower hitch plate, through a separate one of the at least two holes of the shaft, and through one spring each; and an end of each rod being connected to a separate termination for a rope, and another end of each rod being connected to the corresponding spring.
According to an embodiment of the invention, a pivoting hitch for an elevator rope includes a shaft being shaped as a right cylindrical prism, with a base having a circular arc joined at both ends by a straight line whereby the shaft has a flat portion and a rounded circular portion; at least one hole through the shaft, the at least one hole being substantially perpendicular to the flat portion; the rounded circular portion of the shaft resting on a seat, wherein a shape of the seat that makes contact with the shaft is congruent to the rounded circular portion of the shaft; the seat resting on a lower hitch plate; the lower hitch plate having at least one hole therein; at least one rod passing through the at least one hole in the lower hitch plate, through the at least one hole of the shaft, and through at least one spring; an end of the at least one rod being connected to a termination for a rope, and another end of the at least one rod being connected to the spring; and one side of the seat being contained by a hitch weldment and another side of the seat being contained by a side plate; wherein one side of the seat is contained by a hitch weldment and another side of the seat is contained by a side plate; and wherein the elevator rope is reeved from the pivoting hitch over a first sheave, a second sheave, and a drive sheave, and the first and second sheaves are attached to an elevator car that travels through a hoistway; wherein a first portion of the rope is between the pivoting hitch and the first sheave, a second portion of the rope is between the first sheave and the second sheave, a third portion of the rope is between the second sheave and the drive sheave, and a first rope angle between the first and second portions is equal to a second rope angle between the second and third portions.